<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .wrapper {
            background-color: #3a8ee6;
            height: 800px;
            display: flex;
            justify-content: center;
            align-items: baseline;
        }

        .flex1 {
            background-color: #5daf34;
            width: 200px;
            height: 200px;
        }

        .flex2 {
            background-color: #666666;
            height: 200px;
            width: 200px;
            flex: 2;
            display: flex;
            justify-content: center;
            align-items: center;
        }

        .flex3 {
            align-self: baseline;
            background-color: #e76f6f;
            height: 200px;
            width: 200px;
            flex: 2;
        }

        .flex22 {
            background-color: #b3e19d;
            width: 60px;
            height: 20px;
        }

    </style>
</head>
<body>
<div class="wrapper">
    <div class="flex1">盒子1</div>
    <div class="flex2">
        <div class="flex22">
            盒子2
        </div>
    </div>
    <div class="flex3">盒子1</div>
</div>

</body>
</html>